Induction of subcutaneous adipose proliferation by olanzapine in rodents

Mechanisms of adverse mammary effect induced by olanzapine and therapeutic interventions in rat model

BACKGROUND

Olanzapine antagonizes dopamine receptors and is prescribed to treat multiple psychiatric conditions. The main side effect of concern for olanzapine is weight gain and metabolic syndrome. Olanzapine induces hyperprolactinemia, however its effect on the mammary gland is poorly documented.

METHODS

Rats received olanzapine by gavage or in drinking water at 1, 3, and 6 mg/kg/day for 5-40 days or 100 days, with and without coadministration of bromocriptine or aripiprazole and using once daily or continuous administration strategies. Histomorphology of the mammary gland, concentrations of prolactin, estradiol, progesterone, and olanzapine in serum, mammary gland and adipose tissue, and mRNA and protein expressions of prolactin receptors were analyzed.

RESULTS

In adult and prepubescent female rats and male rats, olanzapine induced significant development of mammary glands in dose- and time-dependent manners, with histopathological hyperplasia of mammary ducts and alveoli with lumen dilation and secretion, marked increase of mammary prolactin receptor expression, a marker of breast tissue, and with mild increase of circulating prolactin. This side effect can be reversed after medication withdrawal, but long-term olanzapine treatment for 100 days implicated tumorigenic potentials indicated by usual ductal epithelial hyperplasia. Olanzapine induced mammary development was prevented with the coaddition of the dopamine agonist bromocriptine or partial agonist aripiprazole, or by continuous administration of medication instead of a once daily regimen.

CONCLUSIONS

These results shed light on the previously overlooked effect of olanzapine on mammary development and present experimental evidence to support current clinical management strategies of antipsychotic induced side effects in the breast.

Adipose tissue as a target for second-generation (atypical) antipsychotics: A molecular view

Schizophrenia is a neuropsychiatric disorder that chronically affects 21 million people worldwide. Second-generation antipsychotics (SGAs) are the cornerstone in the management of schizophrenia. However, despite their efficacy in counteracting both positive and negative symptomatology of schizophrenia, recent clinical observations have described an increase in the prevalence of metabolic disturbances in patients treated with SGAs, including abnormal weight gain, hyperglycemia and dyslipidemia. While the molecular mechanisms responsible for these side-effects remain poorly understood, increasing evidence points to a link between SGAs and adipose tissue depots of white, brown and beige adipocytes. In this review, we survey the present knowledge in this area, with a particular focus on the molecular aspects of adipocyte biology including differentiation, lipid metabolism, thermogenic function and the browning/beiging process.

Olanzapine-depot administration induces time-dependent changes in adipose tissue endocrine function in rats

OBJECTIVE

Metabolic adverse effects of atypical antipsychotics (AAP) contribute significantly to increased risk of cardiovascular morbidity and mortality in patients suffering from schizophrenia. Extensive preclinical research has addressed this issue over the past years, though mechanisms underlying these adverse effects of AAP are still not understood completely. Recently, attention is drawn towards the role of adipose tissue metabolism and neurohormonal regulations.

METHODS

The aim of this study was to evaluate the time-dependent effects of olanzapine depot administration at clinically relevant dosing on the regulation of energy homeostasis, glucose and lipid metabolism, gastrointestinal and adipose tissue-derived hormones involved in energy balance regulations in female Sprague-Dawley rats. The study lasted 8 weeks and the markers were assayed at day 8, 15, 29, 43 and 57.

RESULTS

The results indicate that in the absence of hyperphagia, olanzapine chronic exposure induced weight gain from the beginning of the study. In the later time-point, increased adiposity was also observed. In the initial phase of the study, lipid profile was altered by an early increase in triglyceride level and highly elevated leptin level was observed. Clear bi-phasic time-dependent effect of olanzapine on leptin serum concentration was demonstrated. Olanzapine treatment did not lead to changes in serum levels of ghrelin, FGF-21 and pro-inflammatory markers IL-1a, IL-6 and TNF-α at any time-point of the study.

CONCLUSION

This study provides data suggesting early alteration in adipose tissue endocrine function as a factor involved in mechanisms underlying metabolic adverse effects of antipsychotics.

Atypical antipsychotics induce both proinflammatory and adipogenic gene expression in human adipocytes in vitro

Schizophrenia requires lifelong treatment, potentially causing systemic changes in metabolic homeostasis. In the clinical setting, antipsychotic treatment may differentially lead to weight gain among individual patients, although the molecular determinants of such adverse effects are currently unknown. In this study, we investigated changes in the expression levels of critical regulatory genes of adipogenesis, lipid metabolism and proinflammatory genes during the differentiation of primary human adipose-derived stem cells (ADSCs). These cells were isolated from patients with body mass indices <25 and treated with the second-generation antipsychotics olanzapine, ziprasidone, clozapine, quetiapine, aripiprazole and risperidone and the first-generation antipsychotic haloperidol. We found that antipsychotics exhibited a marked effect on key genes involved in the regulation of cell cycle, signal transduction, transcription factors, nuclear receptors, differentiation markers and metabolic enzymes. In particular, we observed an induction of the transcription factor NF-KB1 and NF-KB1 target genes in adipocytes in response to these drugs, including the proinflammatory cytokines TNF-α, IL-1β, IL-8 and MCP-1. In addition, enhanced secretion of both IL8 and MCP-1 was observed in the supernatant of these cell cultures. In addition to their remarkable stimulatory effects on proinflammatory gene transcription, three of the most frequently prescribed antipsychotic drugs, clozapine, quetiapine and aripiprazole, also induced the expression of essential adipocyte differentiation genes and the adipocyte hormones leptin and adiponectin, suggesting that both glucose and fat metabolism may be affected by these drugs. These data further suggest that antipsychotic treatments in patients alter the gene expression patterns in adipocytes in a coordinated fashion and priming them for a low-level inflammatory state.

Effect of atypical antipsychotics on fetal growth: is the placenta involved?

There is currently considerable uncertainty regarding prescribing practices for pregnant women with severe and persistent psychiatric disorders. The physician and the mother have to balance the risks of untreated psychiatric illness against the potential fetal toxicity associated with pharmacological exposure. This is especially true for women taking atypical antipsychotics. Although these drugs have limited evidence for teratological risk, there are reports of altered fetal growth, both increased and decreased, with maternal atypical antipsychotic use. These effects may be mediated through changes in the maternal metabolism which in turn impacts placental function. However, the presence of receptors targeted by atypical antipsychotics in cell lineages present in the placenta suggests that these drugs can also have direct effects on placental function and development. The signaling pathways involved in linking the effects of atypical antipsychotics to placental dysfunction, ultimately resulting in altered fetal growth, remain elusive. This paper focuses on some possible pathways which may link atypical antipsychotics to placental dysfunction.

A randomized, placebo-controlled study of zonisamide to prevent olanzapine-associated weight gain

Weight gain is commonly observed with olanzapine treatment. Zonisamide is an antiepileptic drug associated with weight loss. This study examined the effectiveness of zonisamide in preventing weight gain in 42 patients beginning olanzapine for bipolar disorder or schizophrenia. Each patient had a body mass index of 22 mg/kg or greater and was randomized to taking olanzapine with either zonisamide (n = 20) or placebo (n = 22) for 16 weeks. The primary outcome measure was change in body weight in kilograms from baseline. In the primary analysis using longitudinal regression, patients who received zonisamide had a significantly slower rate of weight gain and increase in body mass index than those who received placebo. The patients treated with zonisamide gained a mean (SD) of 0.9 (3.3) kg, whereas those treated with placebo gained a mean (SD) of 5.0 (5.5) kg; P = 0.01. None of the patients in the zonisamide group, compared with 7 patients (33%) in the placebo group, gained 7% of body weight or greater from baseline (Fisher exact test, P = 0.009). The zonisamide group, however, reported significantly more cognitive impairment as an adverse event than the placebo group (25% vs 0, respectively; P = 0.02). Zonisamide was effective for mitigating weight gain in patients with bipolar disorder or schizophrenia initiating treatment with olanzapine but was associated with cognitive impairment as an adverse event.